Aqua Tunes: Why Do We Hear Sounds Differently Underwater?

By Accessible Science on Jun 10, 2014

Perkins School for the Blind student Jamie LeDuc shares his science fair research experiment "Why Do We Hear Sounds Differently Under Water?"
 
 
Listen Here for Jamie's Radio Interview: 
 

Topic:

Why do we hear sounds differently underwater?
 

Hypothesis:

I think we hear sounds differently because sound travels faster in water which creates a distortion.
 

Design your experiment:

Using headphones and music, I'm trying to find out what happens when sound travels in water.
 

 

Materials

  • Two plastic bags filled with water
  • A roll of duct tape
  • Two pairs of headphones
  • An iPad

Procedure

  1. student listening to sound through plastic bags filled with waterFill two plastic bags with water and tape the seals as a caution.
  2. Use duct tape to tape the speakers of the headphones to the bags.
  3. Plug headphones into the iPad and play music.
  4. Listen to music. Make sure that the portion of the bags that contains water is on your ears.
  5. Take second pair of headphones and plug them into the iPad.
  6. Play music and check if there are any differences in how it sounds.

Observations:

The underwater headphones: The sound was muffled, yet I could hear the lower frequencies of the music more easily. The regular headphones: The sound was louder and I found it easier to hear music with higher frequencies. It was much harder to decipher lower frequencies.  

Conclusion:

Unfortunately, the experiment did not answer my scientific question.  Therefore, research was required. student on radio interview  

Research:

Ironically, sound waves travel 4.3 times faster underwater than they do through air.  This is because water is denser than air.  Since sound waves travel so much faster underwater than in air, it is much harder for us to detect where they are coming from.  Our bodies have something called bone conductivity.  This is a process in which the mastoid, the bone behind our ears, takes in sounds.  This allows sound to skip the outer ear all together, making it to the cochlea and eventually sending signals to the brain.  Underwater, humans can actually hear sounds at much higher frequencies then they can on land.  The reason that my experiment showed different results is because I was not actually underwater.  However, if I had been listening to music underwater, I would have heard higher frequencies that I may not have noticed otherwise.    

Resources:

oceanservice.noaa.gov/facts/sound.html     Aqua tunes collage

 

 

Read more about: STEM